三磷酸肌醇在IL—2诱导的T细胞增殖分化中的信息传递作用

用不同浓度的IL-2刺激静息T淋巴细胞,其细胞内IP_3无明显改变,但ConA刺激则使IP_3增加45%。在IL-2依赖性T细胞,IL-2R表达率达83%,IL-2刺激时IP_3的变化依浓度不同而异,10u—50u/ml的IL-2使IP_3增高,以50u/ml最为显著,增加60%,但100u/ml IL-2及ConA不改变胞内IP_3的浓度。IL-2R封闭后的T淋巴细胞在IL-2刺激时IP_3的增加明显减弱。这些结果提示:IP_3作为细胞内的第二信使介导了IL-2诱导的T细胞的增殖反应,这种作用与IL-2的剂量及IL-2R表达有密切的关系。     

完美主义对心理健康、自尊及主观幸福感的影响

目的探讨大学生完美主义对心理健康、自尊和主观幸福感的影响作用.方法采用完美主义量表、心理健康量表、自尊量表和幸福感量表对290名大学生进行测试.结果①担心出错、对行动的疑虑是心理健康的影响变量;担心出错、组织性和对行动的疑虑是自尊的影响变量;担心出错和组织性是主观幸福感的影响变量.②顺应不良的完美主义对心理健康、自尊及主观幸福感产生消极影响;顺应良好的完美主义对自尊和主观幸福感产生积极影响.结论完美主义维度对心理健康、自尊及主观幸福感具有不同程度的影响,顺应良好和顺应不良的完美主义对心理健康、自尊及主观幸福感具有不同性质的影响.     

Cortical representation of space around the blind spot

The neural mechanism that mediates perceptual filling-in of the blind spot is still under discussion. One hypothesis proposes that the cortical representation of the blind spot is activated only under conditions that elicit perceptual filling-in and requires congruent stimulation on both sides of the blind spot. Alternatively, the passive remapping hypothesis proposes that inputs from regions surrounding the blind spot infiltrate the representation of the blind spot in cortex. This theory predicts that independent stimuli presented to the left and right of the blind spot should lead to neighboring/overlapping activations in visual cortex when the blind-spot eye is stimulated but separated activations when the fellow eye is stimulated. Using functional MRI, we directly tested the remapping hypothesis by presenting flickering checkerboard wedges to the left or right of the spatial location of the blind spot, either to the blind-spot eye or to the fellow eye. Irrespective of which eye was stimulated, we found separate activations corresponding to the left and right wedges. We identified the centroid of the activations on a cortical flat map and measured the distance between activations. Distance measures of the cortical gap across the blind spot were accurate and reliable (mean distance: 6-8 mm across subjects, SD approximately 1 mm within subjects). Contrary to the predictions of the remapping hypothesis, cortical distances between activations to the two wedges were equally large for the blind-spot eye and fellow eye in areas V1 and V2/V3. Remapping therefore appears unlikely to account for perceptual filling-in at an early cortical level.     

Extracellular pH changes and accompanying cation shifts during ouabain-induced spreading depression

Interstitial ionic shifts that accompany ouabain-induced spreading depression (SD) were studied in rat hippocampal and cortical slices in the presence and absence of extracellular Ca(2+). A double-barreled ion-selective microelectrode specific for H(+), K(+), Na(+), or Ca(2+) was placed in the CA1 stratum radiatum or midcortical layer. Superfusion of 100 microM ouabain caused a rapid, negative, interstitial voltage shift (2-10 mV) after 3-5 min. The negativity was accompanied by a rapid alkaline transient followed by prolonged acidosis. In media containing 3 mM Ca(2+), the alkalosis induced by ouabain averaged 0.07 +/- 0.01 unit pH. In media with no added Ca(2+) and 2 mM EGTA, the alkaline shift was not significantly different (0.09 +/- 0.02 unit pH). The alkaline transient was unaffected by inhibiting Na(+)-H(+) exchange with ethylisopropylamiloride (EIPA) or by blocking endoplasmic reticulum Ca(2+) uptake with thapsigargin or cyclopiazonic acid. Alkaline transients were also observed in Ca(2+)-free media when SD was induced by microinjecting high K(+). The late acidification accompanying ouabain-induced SD was significantly reduced in Ca(2+)-free media and in solutions containing EIPA. The ouabain-induced SD was associated with a rapid but relatively modest increase in [K(+)](o). In the presence of 3 mM external Ca(2+), the mean peak elevation of [K(+)](o) was 12 +/- 0.62 mM. In Ca(2+)-free media, the elevation of [K(+)](o) had a more gradual onset and reached a significantly larger peak value, which averaged 22 +/- 1.1 mM. The decrease in [Na(+)](o) that accompanied ouabain-induced SD was somewhat greater. The [Na(+)](o) decreased by averages of 40 +/- 7 and 33 +/- 3 mM in Ca(2+) and Ca(2+)-free media, respectively. In media containing 1.2 mM Ca(2+), ouabain-induced SD was associated with a substantial decrease in [Ca(2+)](o) that averaged 0.73 +/- 0. 07 mM. These data demonstrate that in comparison with conventional SD, ouabain-induced SD exhibits ion shifts that are qualitatively similar but quantitatively diminished. The presence of external Ca(2+) can modulate the phenomenon but is irrelevant to the generation of the SD and its accompanying alkaline pH transient. Significance of these results is discussed in reference to the propagation of SD and the generation of interstitial pH changes.     

Caffeine and histamine-induced oscillations of K(Ca) current in single smooth muscle cells of rabbit cerebral artery

In the present experiment, we characterized the intracellular Ca²⁺ oscillations induced by caffeine (1 mM) or histamine (1–3 M) in voltage-clamped single smooth muscle cells of rabbit cerebral (basilar) artery. Superfusion of caffeine or histamine induced periodic oscillations of large whole-cell K⁺ current with fairly uniform amplitudes and intervals. The oscillatory K⁺ current was abolished by inclusion of ethylenebis(oxonitrilo)tetraacetate (EGTA, 5 mM) in the pipette solution. Caffeine- and histamine-induced periodic activation of the large-conductance Ca²⁺-activated K⁺ [K_(Ca)] channel was recorded in the cell-attached patch mode. These results suggest that the oscillations of K⁺ current are carried by the K_(Ca) channel and reflect the oscillations of intracellular Ca²⁺ concentration ([Ca²⁺]_i). Ryanodine (1–10 M) abolished both caffeine- and histamine-induced oscillations. Caffeine- induced oscillations were abolished by the sarcoplasmic reticulum Ca²⁺-adenosine 5-triphosphatase (Ca²⁺-ATPase) inhibitor, cyclopiazonic acid (10 M), and a high concentration of caffeine (10 mM). Inclusion of heparin (3 mg/ml) in the pipette solution blocked histamine-induced oscillations, but did not block caffeine-induced oscillations. By the removal of extracellular Ca²⁺, but not by the addition of verapamil and Cd²⁺, the caffeine-induced oscillations were abolished. Increasing Ca²⁺ influx rate increased the frequencies of caffeine-induced oscillations. Spontaneous oscillations were also observed in cells that were not superfused with agonists, and had similar characteristics to the caffeine-induced oscillations. From the above results, it is concluded, that in smooth muscle cells of the rabbit cerebral (basilar) artery, ryanodine-sensitive Ca²⁺-induced Ca²⁺ release pools play key roles in the generation of caffeine- and histamine-induced intracellular Ca²⁺ oscillations.     

Single-step nested polymerase chain reaction for detection of different genotypes of hepatitis C virus

Hepatitis C virus (HCV) exhibits considerable sequence variability and circulates in the blood at extremely low levels. Current methods for detecting HCV RNA are based mostly on nested polymerase chain reaction (PCR), in which part of the first amplification product is reamplified in the second tube by an internal primer pair. A novel nested PCR method was developed in which the two successive amplification processes are carried out in the same tube with a single step of physical manipulation. Careful selection of highly conserved sequences of the 5′ noncoding region as primers enabled successful detection of all three major genotypes circulating in France, including the one with variation in this region. Retaining high sensitivity of the conventional nested PCR, the novel method reduced greatly the risk of carry-over contaminations. It was also cost- and time-saving. The one-step nested PCR method is especially suitable for routine diagnosis of HCV infection in clinical laboratories. © 1995 Wiley-Liss, Inc.     

Effect of stretch on calcium channel currents recorded from the antral circular myocytes of guinea-pig stomach

The effect of membrane stretch on voltage-activated Ba²⁺ current (I _Ba) was studied in antral circular myocytes of guinea-pig using the whole- cell patch-clamp technique. The changes in cell volume were elicited by superfusing the myocytes with anisosmotic solutions. Hyposmotic superfusate (202 mosmol/l) induced cell swelling and increased peak values of I _Ba at 0 mV (from −406.6 ± 45.5 pA to −547.5 ± 65.6 pA, mean ± SEM, n = 8) and hyperosmotic superfusate (350 mosmol/l) induced cell shrinkage and decreased peak values of I _Ba at 0 mV (to −269.5 ± 39.1 pA, n = 8). Such changes were reversible and the extent of change was dependent on the osmolarity of superfusate. The values of normalized I _Ba at 0 mV were 1.43 ± 0.04, 1.30 ± 0.06, 1.23 ± 0.04, 1.19 ± 0.04, 1 and 0.68 ± 0.06 at 202, 220, 245, 267, 290 and 350 mosmol/l, respectively (n = 8). I _Ba was almost completely blocked by nicardipine (5 μM) under hyposmotic conditions. The values of steady-state half-inactivation voltage (−37.7 ± 3.3 and −36.5 ± 2.6 mV, under control and hyposmotic conditions, respectively) or the half-activation voltage (−13.6 ± 2.3 and −13.9 ± 1.9 mV) of I _Ba were not significantly changed (P > 0.05, n = 6). Cell membrane capacitance was slightly increased from 50.00 ± 2.86 pF to 50.22 ± 2.82 pF by a hyposmotic superfusate (P < 0.05, n = 6). It is suggested that cell swelling increases voltage-operated L-type calcium channel current and that such a property is related to the response of gastric smooth muscle to mechanical stimuli. Received: 14 November 1995/Received after revision and accepted: 8 January 1996     

Persistent infection of SARS coronavirus in colonic cells in vitro

Severe acute respiratory syndrome coronavirus (SARS-CoV) can produce gastrointestinal symptoms. The intestinal tract is the only extrapulmonary site where viable viruses have been detected. This study examined seven established human intestinal cell lines, DLD-1, HCT-116, HT-29, LoVo, LS-180, SW-480 and SW-620, for their permissiveness to SARS-CoV infection. The results showed that only LoVo cells were permissive to SARS-CoV infection as evident by positive findings from indirect immunofluorescence staining for intracellular viral antigens, in situ hybridization for intracellular viral RNA, and electron microscopy for intracellular viral particles. In contrast to Vero cells, SARS-CoV did not produce cytopathic effects on LoVo cells. However, LoVo cells were found to be highly permissive for productive infection with a high viral titre (>3 x 10(7) viral copies/ml) produced in culture supernatant following a few days of incubation. SARS-CoV established a stable persistent chronic infection that could be maintained after multiple passages. Being a cell line of human origin, LoVo cells could be a useful in vitro model for studying the biology and persistent infection of SARS-CoV. Our results on the expression of angiotensin-converting enzyme 2 (ACE2), a recently identified cellular receptor for SARS-CoV, in these cell lines indicated that it might not be the sole determinant for cells to be susceptible to SARS-CoV infection.     

骨形成蛋白-7对人肾小管上皮细胞株HK-2凋亡的影响

研究不同浓度的骨成形蛋白 7(BMP 7)对人近曲小管上皮细胞株HK 2凋亡的影响并初步探讨其可能的机制。应用Hoechst 332 5 8荧光染色、DNA电泳检测凋亡细胞的形态学和生化改变 ,流式细胞仪定量检测细胞的凋亡率 ,并观察凋亡特异性蛋白酶Caspase 3活性变化的情况。结果显示 ,HK 2细胞加入 1 0ng/mlTGF β处理 2 4h后 ,可明显抑制细胞生长并诱导细胞凋亡 ,呈现明显的凋亡形态学改变 ,胞核或核质内可见浓度致密的颗粒状荧光 ,DNA电泳呈现典型的“梯形条带” ,而预先加入 5 0ng/ml、 1 0 0ng/mlBMP 7共处理 2 4h后 ,可减轻TGF β对细胞的抑制作用 ,凋亡细胞亦减少 ,Caspase 3蛋白酶活性明显下降 ,细胞凋亡率下降。提示BMP 7对人肾小管上皮细胞凋亡的具有抑制作用 ,可能是通过抑制Caspase蛋白酶活性而实现的